Coating ablating apparatus with coating removal detection

ABSTRACT

A laser-based coating removal apparatus to remove a coating from a surface without damaging the surface. The apparatus comprises a laser source to provide a laser light, a routing element coupled to the laser source and configured to direct the laser light onto a target region of the surface thereby removing the coating from the target region, and a detection element to detect the coating as the coating separates from the target region of the surface. The detection element is able to prevent the surface from being damaged by limiting or eliminating the laser light directed onto the target region after all the coating has been removed. The detection element is able to detect the separation of the coating from the target region by detecting incandescence, acoustic signature, motion, fluorescence and/or chemical properties produced by the separation of the coating from the surface.

RELATED APPLICATIONS

This application claims priority of U.S. provisional application, Ser. No. 61/362,976, filed Jul. 9, 2010, and entitled “Non-Color Sensing for Laser Decoating,” which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to ablating a coating using a laser. In particular, the invention relates to a coating ablating apparatus for detecting the removal of a coating from a surface using a laser to prevent surface damage.

BACKGROUND OF THE INVENTION

Laser-based coating removal systems use pulses of light from high power lasers to ablate or vaporize the paint or other coating from a surface. Each pulse removes the coating from a small region, typically 0.1 to 100 square mm. The laser is pointed to a different area after each pulse, where the removal process is repeated until the entire surface is cleaned. An advantage of lasers for coating removal is that each laser pulse removes a predictable portion of the thickness of the coating, in the small region impacted by the pulse. This opens the possibility of selective stripping where, for example, the topcoat could be removed but not the primer.

A problem with laser de-coating systems is the possibility of damaging the surface if the stripping process is continued after all the coating is removed. A particular source of the possible damage is the result of overheating the surface due to the absorption of the excess laser light by the surface after the coating has been removed. Previous techniques to overcome this problem have relied on measuring the color of the surface at each point within the laser scan field prior to firing the laser at that point. However, these techniques do not work well if the distance and the angle from the laser optics to the substrate vary widely as is the case in many handheld laser de-coating systems on non-flat surfaces.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to a laser-based coating removal apparatus to remove a coating from a surface without damaging the surface. The apparatus comprises a laser source to provide a laser light, a routing element coupled to the laser source and configured to direct the laser light onto a target region of the surface thereby removing the coating from the target region, and a detection element to detect the coating as the coating separates from the target region of the surface. The detection element is able to prevent the surface from being damaged by limiting or eliminating the laser light directed onto the target region after all the coating has been removed. The detection element is able to detect the separation of the coating from the target region by detecting incandescence, acoustic signature, motion, fluorescence and/or chemical properties produced by the separation of the coating from the surface.

In one aspect the present application relates to a laser-based coating removal apparatus to remove a coating from a surface. The apparatus comprises a laser source to provide a laser light, a routing element coupled to the laser source and configured to direct the laser light onto a target region of the surface and a detection element to detect the coating as the coating separates from the target region of the surface. In some embodiments, the detection element detects the separation of the coating from the target region by detecting one or more coating properties selected from the group consisting of the incandescence, acoustic signature, motion, fluorescence and chemical properties. In some embodiments, the routing element transmits a signal related the one or more coating properties to the detection element such that the detection element is able to detect if the coating is separating from the target region. In some embodiments, the rate at which the laser light is directed onto the surface is adjusted based on whether the detection element detects that the coating is separating from the target region. In some embodiments, if the detection element does not detect the coating separating from the target region for a period, a controller coupled to the detection element decreases the rate at which the laser light is directed onto the target region to a preselected low rate. In some embodiments, the controller is able to adjust the length of the period based on one or more characteristics of the target region. In some embodiments, the controller is able to adjust the level of the low rate based on the one or more characteristics of the target region. In some embodiments, if the detection element detects the coating separating from the target region while the rate at which the laser light is directed onto the target region is equal to the low rate, the controller increases the rate at which the laser light is directed onto the target region to a preselected high rate. In some embodiments, the controller is able to adjust the level of the high rate based on the one or more characteristics of the target region. In some embodiments, the one or more characteristics of the target region comprise a temperature of the target region. In some embodiments, the high rate is equal to continuous projection of the laser light onto the target region and the low rate is equal to none of the laser light being projected onto the target region. In some embodiments, the high rate and the low rate are proportional to each other such that if one of the high or low rate is adjusted, the other rate is also adjusted in proportion. In some embodiments, the detection element divides the target region into a plurality of detection areas and if the detection element does not detect the coating separating from the target region in one or more of the detection areas for the period, the controller decreases the rate at which the laser light is directed onto the target region to the preselected low rate.

A second aspect of the present application is directed to a laser-based coating removal system. The system comprises a surface having a coating and a laser-based removal apparatus comprising a laser source to provide a laser light, a routing element coupled to the laser source and configured to direct the laser light onto a target region of the surface and a detection element to detect the coating as the coating separates from the target region of the surface. In some embodiments, the detection element detects the separation of the coating from the target region by detecting one or more coating properties selected from the group consisting of the incandescence, acoustic signature, motion, fluorescence and chemical properties. In some embodiments, the routing element transmits a signal related the one or more coating properties to the detection element such that the detection element is able to detect if the coating is separating from the target region. In some embodiments, the rate at which the laser light is directed onto the surface is adjusted based on whether the detection element detects that the coating is separating from the target region. In some embodiments, if the detection element does not detect the coating separating from the target region for a period, a controller coupled to the detection element decreases the rate at which the laser light is directed onto the target region to a preselected low rate. In some embodiments, the controller is able to adjust the length of the period based on one or more characteristics of the target region. In some embodiments, the controller is able to adjust the level of the low rate based on the one or more characteristics of the target region. In some embodiments, if the detection element detects the coating separating from the target region while the rate at which the laser light is directed onto the target region is equal to the low rate, the controller increases the rate at which the laser light is directed onto the target region to a preselected high rate. In some embodiments, the controller is able to adjust the level of the high rate based on the one or more characteristics of the target region. In some embodiments, the one or more characteristics of the target region comprise a temperature of the target region. In some embodiments, the high rate is equal to continuous projection of the laser light onto the target region and the low rate is equal to none of the laser light being projected onto the target region. In some embodiments, the high rate and the low rate are proportional to each other such that if one of the high or low rate is adjusted, the other rate is also adjusted in proportion. In some embodiments, the detection element divides the target region into a plurality of detection areas and if the detection element does not detect the coating separating from the target region in one or more of the detection areas for the period, the controller decreases the rate at which the laser light is directed onto the target region to the preselected low rate.

Another aspect of the present application is directed to a laser-based method of removing a coating from a surface. The method comprises activating a laser source to provide a laser light, directing the laser light onto a target region of the surface with a routing element and detecting if the coating is separating from the target region of the surface with a detection element. In some embodiments, the detection element detects the separation of the coating from the target region by detecting one or more coating properties selected from the group consisting of the incandescence, acoustic signature, motion, fluorescence and chemical properties. The method further comprises transmitting a signal related the one or more coating properties with the routing element to the detection element such that the detection element is able to detect if the coating is separating from the target region. The method further comprises adjusting the rate at which the laser light is directed onto the surface based on whether the detection element detects that the coating is separating from the target region. The method further comprises decreasing the rate at which the laser light is directed onto the target region to a preselected low rate if the detection element does not detect the coating separating from the target region for a period. The method further comprises adjusting the length of the period based on one or more characteristics of the target region. The method further comprises adjusting the level of the low rate based on the one or more characteristics of the target region. The method further comprises increasing the rate at which the laser light is directed onto the target region to a preselected high rate if the detection element detects the coating separating from the target region while the rate at which the laser light is directed onto the target region is equal to the low rate. The method further comprises adjusting the level of the high rate based on the one or more characteristics of the target region. In some embodiments, the one or more characteristics of the target region comprise a temperature of the target region. In some embodiments, the high rate is equal to continuous projection of the laser light onto the target region and the low rate is equal to none of the laser light being projected onto the target region. In some embodiments, the high rate and the low rate are proportional to each other such that if one of the high or low rate is adjusted, the other rate is also adjusted in proportion. The method further comprises decreasing the rate at which the laser light is directed onto the target region to the preselected low rate if the detection element does not detect the coating separating from the target region in one or more of a plurality of detection areas for the period, wherein the detection areas each comprise a portion of the target region. The method further comprises adjusting the size of the detection areas based on the characteristics of the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an exemplary block diagram of the coating removal system having a common detection path according to some embodiments.

FIG. 1B illustrates an exemplary block diagram of the coating removal system having a separate detection path according to some embodiments.

FIG. 2A illustrates a more detailed diagram of an exemplary block diagram of the coating removal system having a common detection path according to some embodiments.

FIG. 2B illustrates a more detailed diagram of an exemplary block diagram of the coating removal system having a separate detection path according to some embodiments.

FIG. 3 illustrates a flow chart of a method of removing a coating from a surface according to some embodiments.

Embodiments of the coating removal device are described relative to the several views of the drawings. Where appropriate and only where identical elements are disclosed and shown in more than one drawing, the same reference numeral will be used to represent such identical elements.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Embodiments of the present invention are directed to a laser-based coating removal apparatus to remove a coating from a surface without damaging the surface. The apparatus comprises a laser source to provide a laser light, a routing element coupled to the laser source and configured to direct the laser light onto a target region of the surface thereby removing the coating from the target region, and a detection element to detect the coating as the coating separates from the target region of the surface. The detection element is able to prevent the surface from being damaged by limiting or eliminating the laser light directed onto the target region after all the coating has been removed. The detection element is able to detect the separation of the coating from the target region by detecting incandescence, acoustic signature, motion, fluorescence and/or chemical properties produced by the separation of the coating from the surface.

Reference will now be made in detail to implementations of the laser-based coating removal apparatus as illustrated in the accompanying drawings. The same reference indicators will be used through the drawings and the following detailed description to refer to the same or like parts. In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will also be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions be made to achieve the developer's specific goals, such as compliance with application and business related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.

FIG. 1A illustrates an exemplary block diagram of a coating removal system 100 using a common path according to some embodiments. The coating removal system 100 comprises a laser source 102, a routing element 104, a detection element 106 and a controller 108 for removing a coating 98 from a surface 99. In some embodiments, the system 100 comprises one or more additional laser sources 102, routing elements 104, detection elements 106 and/or controllers 108. The laser source 102 is able to comprise one or more lasers. Alternatively, the laser source 102 is able to comprise other components capable of outputting laser light 97 (see FIGS. 2A and 2B) as are well known in the art. The laser source 102 is coupled to routing element 104 such that laser light 97 output by the laser source 102 is received by the routing element 104 such that the routing element 104 is able to manipulate and direct/route the laser light 97 onto the desired portion of the surface 99 having the coating 98 to be removed. Specifically, the routing element 104 is optically coupled to the surface 99/coating 98 such that the routing element 106 is able to direct the laser light 97 received from the laser source 102 onto the surface 99 to effectuate the removal of the coating 98 from the surface 99.

As shown in FIG. 1A, the routing element 104 is also coupled to the input of the detection element 106 such that one or more of the properties of the surface 99 and/or the coating 98 (as the coating 98 is being removed from the surface 99), are able to be transmitted to the detection element 106 by the routing element 104. In other words, both the laser source 102 and the detection element 106 are able to use a common path through the routing element 104 to access the surface 99 and/or coating 98. For example, components of the routing element 104 used for routing the laser light 97 to the surface 99 are able to be used to receive incandescent light from the coating 98 caused by the removal of the coating 98 from the surface 99 and transmit that received incandescent light (or a signal 96 corresponding to the incandescent light (see FIG. 2A)) to the detection element 106. Alternatively, signals 96 corresponding to other properties of the surface 99 and/or coating 98 are able to be transmitted to the detection element 106 by the routing element 104 such as acoustic signature, motion, fluorescence and other detectable chemical properties of the surface 99/coating 98 as are well known in the art. The detection element 106 is able to receive the one or more signals of properties 96 corresponding to the surface 99 and/or coating 98 from the routing element 104 and determine if the coating 98 is currently separating from the surface 99. Specifically, the detection element 106 is able to determine if the coating 98 is currently separating from the surface 99 by determining if the detected properties exceed a preselected threshold indicating that separation is currently occurring in the detected area of the surface 99.

The controller 108 is coupled to the detection element 106 and the laser source 102 such that the controller 108 is able to control the operation of the laser source 102 based on the output received from the detection element 106. Specifically, the controller 108 is able to adjust the rate and/or intensity at which the laser light 97 is output by the laser source 102 based on whether the output of the detection element 106 indicates that the coating 98 is currently being removed or if the removal of the coating 98 is no longer being detected. As a result, during the process of removing the coating 98 from the surface 99, the system 100 is able to determine when the coating 98 is no longer being removed from the surface 99 (e.g. all the coating 98 has been removed) and lower or raise the rate and/or intensity of the laser light 97 output onto the surface 99 accordingly in order to efficiently remove the coating 98 while preventing the surface 99 from being damaged from the laser light 97. The controller 108 is able to comprise various designs of one or more electronic devices well known in the art which are not discussed herein for the sake of brevity. In some embodiments, one or more of the components of the coating removal system 100 are incorporated into a single coating removal apparatus. Alternatively, the components of the coating removal system 100 are able to comprise multiple devices.

FIG. 1B illustrates an exemplary block diagram of the coating removal system 100′ having a separate detection path according to some alternative embodiments. The system 100′ shown in FIG. 1B is substantially similar to the system 100 except for the differences described herein. Specifically, the detection element 106 of the system 100′ is coupled directly to the surface 99 and/or the coating 98 forming a separate detection path instead of coupling through the routing element 104. The manner in which the detecting element 106 is coupled to the surface 99/coating 98 depends on the one or more types of surface 99/coating 98 properties used to determine if the coating 98 is currently being removed. For example, if the incandescence produced by the removed coating 98 is to be detected, the detecting element 106 is optically coupled to the surface 99/coating 98. Alternatively, other manners of coupling or combination of manners of coupling are able to be used as are well known in the art in order to detect one or more of incandescence, acoustic signature, motion, fluorescence and other detectable chemical properties of the surface 99/coating 98. As a result, the detection element 104 is able to directly monitor and receive signals 96 (see FIG. 2B) from the surface 99 and/or coating 98 as the system 100′ is operating and output to the controller 108 whether the removal of the coating 98 is currently detected. Alternatively, the detection element 106 is able to be coupled to both the routing element 104 and the surface 99/coating 98 such that the detection element 106 is able to receive signals 96 corresponding to the properties of the coating 98 and/or surface 99 as the coating 98 is removed from the surface 99 from the surface 99/coating 98 directly, via the routing element 104 or both.

FIG. 2A illustrates a more detailed diagram of a coating removal system 100 using a common path according to some embodiments. As shown in FIG. 2A, the routing element 104 comprises a beam splitter 202, focusing optics 204 and scanning optics 206. The focusing optics 204 receive and focus light passing through the beam splitter 202 from the light source 102 to the scanning optics 206 which align and focus the laser light 97 onto the coating/surface 98, 99. The scanning optics 206 also receive signals 96 (e.g. incandescent light from gaseous removed coating 98) that are routed from the scanning optics 206 to the beam splitter 202 (via the focusing optics 204). The beam splitter 202 receives the signals 96 and routes the signals 96 to the detection element 106. As a result, the routing element 104 is able to utilize the common path to simultaneously route the laser light 97 onto the surface/coating 98, 99 and receives/transmits signals 96 (e.g. detected coating 98 gaseous incandescence upon removal) related to one or more properties of the removal of the coating 98 from the surface 99 to the detection element 106 for determining the state of the coating removal process. It is understood that the routing element 104 is able to comprise less or more components for routing the laser light 97 and/or transmitting the surface/coating signals 96 to the detection element 106 as are well known in the art. For example, in some embodiments, the routing element 104 is able to comprise audio, electrical and/or chemical detection and transmission elements enabling the routing element 104 to use the common path to simultaneously route, in addition to light, audio, electrical, chemical and/or other types of signals 96 related to the properties of the removal of the coating 98 from the surface 99 to the detection element 106.

As also shown in FIG. 2A, the detection element 106 comprises an input interface 208, a signal detector 210 and a comparator 212. In some embodiments, the input interface 208 comprises an input lens for receiving a light signal 96. Alternatively, the input interface 208 is able to comprise one or more other components for receiving audio, visual, electrical, chemical and other types of signals 96 as are well known in the art. In some embodiments, the signal detector 210 is a photosensitive device such as a photodiode for receiving a light signal. Alternatively, the signal detector 210 is able to be other detecting devices such as a microphone or other types of detectors able to detect one or more of incandescence, acoustic signature, motion, fluorescence and other detectable chemical properties of the surface 99/coating 98. For example, in order to detect an acoustic signature of the separating coating 98, the signal detector 210 is able to comprise a microphone for converting the received audio signal to a desired corresponding signal and a filter to separate sounds generated from the separated coating 98 from other noise. In some embodiments, the comparator 212 comprises an amplifier for comparing the signal 96 to a threshold voltage. Alternatively, the comparator 212 is able to comprise other components for comparing a received signal 96 to a reference as are well known in the art.

In operation, the input interface 208 receives the signals 96 from the routing element 104 and transmits the signals 96 to the signal detector 210. The signal detector 210 converts the received signal 96 to a desired corresponding signal and transmits the corresponding signal to the comparator 212 which determines if the received corresponding signal indicates that the coating 98 is currently being removed from the surface 99. In some embodiments, the comparator 212 makes this determination by determining if a voltage of the corresponding signal exceeds a predetermined threshold voltage. Alternatively, the comparator 212 is able to make the determination based on voltage and/or one or more other properties of the corresponding signal as are well known in the art. As a result, the detection element 106 is able to output a detection signal to the controller 108 indicating whether the coating 98 is currently being detected as being currently removed from the surface 99. It is understood that the detection element 106 is able to comprise less or more components for determining if the surface/coating signals 96 indicate that the coating 98 is currently being removed from the surface 99 as are well known in the art. For example, the input interface 208 is able to be omitted and the signal 96 is able to be received directly by the signal detector 210.

As described above in relation to FIG. 1A, the controller 108 adjusts the rate and/or intensity at which the laser light 97 is output by the laser source 102 based on whether the coating 98 is currently being removed or if the removal of the coating 98 is no longer being detected. In some embodiments, the controller 108 increases the intensity and/or rate/frequency at which the light 97 is output from a predetermined low level to a predetermined high level when the removal of the coating 98 is detected. For example, the controller 108 is able to increase the rate and/or intensity from 0 or 1% of the normal rate/intensity to 100% of the normal rate/intensity upon detecting the removal of the coating 98. Alternatively, the low and high levels are able to be other percentages of the normal rate/intensity or preselected rate/intensity values. Alternatively, the rate and/or intensity is able to be adjusted gradually/incrementally by the controller 108. In some embodiments where both rate and intensity values are adjusted, the rate value and frequency value are able to be adjusted to different levels dependently or independently.

Similarly, in some embodiments, the controller 108 decreases the intensity and/or rate at which the light 97 is output from the predetermined high level to the predetermined low level when the removal of the coating 98 is not detected for a period. In some embodiments, the period is 50 milliseconds. Alternatively, other periods are contemplated. In some embodiments, the period, predetermined high level and/or predetermined low level are able to be adjusted based on the characteristics of the surface 99. For example, if the rate of change of the surface temperature is low, the surface temperature is low and/or the surface is able to endure high temperatures before becoming damaged, the period and/or low level is able to be increased to reflect the resistance to damage of the surface 99. As a result, during the process of removing the coating 98 from the surface 99, the system 100 is able to determine when the coating 98 is no longer being removed from the surface 99 (e.g. all the coating 98 has been removed) and lower the rate and/or intensity of the laser light 97 output onto the surface 99 in order to prevent the surface 99 from being damaged from the laser light 97.

FIG. 2B illustrates a more detailed diagram of a coating removal system 100′ with a separate detection path according to some embodiments. The system 100′ shown in FIG. 2B is substantially similar to the system 100 shown in FIG. 2A except for the differences described herein. Specifically, the input interface 208 of the detection element 106 of the system 100′ is coupled directly to the surface 99 and/or the coating 98 forming a separate detection path instead of coupling through the routing element 104. As described above in relation to FIG. 1B, the manner in which the input interface 208 is coupled to the surface 99/coating 98 depends on the one or more types of surface 99/coating 98 properties used to determine if the coating 98 is currently being removed. For example, if the incandescence produced by the removed coating 98 is to be detected, the input interface 208 is able to comprise a lens that is optically coupled to the surface 99/coating 98. Alternatively, other manners of coupling or combination of manners of coupling are able to be used as are well known in the art in order to detect one or more of incandescence, acoustic signature, motion, fluorescence and other detectable chemical properties of the surface 99/coating 98. As a result, the detection element 104 is able to directly monitor and receive signals 96 from the surface 99 and/or coating 98 as the system 100′ is operating and output the detection signal to the controller 108 indicating whether the removal of the coating 98 is currently detected. In some embodiments, the input interface 208 is able to be coupled to both the routing element 104 and the surface 99/coating 98 such that the detection element 106 is able to receive signals 96 corresponding to the properties of the coating 98 and/or surface 99 as the coating 98 is removed from the surface 99 from the surface 99/coating 98 directly, via the routing element 104 or both. In some embodiments, the input interface 208 is able to be omitted and instead the signal detector 210 is able to be coupled directly to the surface 99/coating 98, via the routing element 104 or both.

In some embodiments, the detection element 104 is able to define a plurality of detection areas, which are a fraction of a target area of the surface 99/coating 98 contacted by the laser light 97 during the removal process, in order to guard against the situation where one area of the target surface is being damaged even though coating removal is still being detected in another part of the target area. Specifically, using the smaller detection areas, the detection element 104 to able to individually detect whether coating removal is absent in one or more of the detection areas and lower the laser rate and/or intensity even though coating removal is still being detected in another detection area (i.e. another part of the target area). Thus, by refining the size/number of detection areas defined within the target area, the system 100, 100′ is able to minimize the chance that current coating removal at one end of the target area is able to occur while another end of the target area is being damaged. In some embodiments, the system 100, 100′ is also able to reduce the risk of damage by enabling a user to selectively choose the one or more types of properties of the surface 99/coating 98 the system 100, 100′ should detect in order to determine if the coating 98 is currently being removed. For example, a user is able to select one or a combination of light, audio and chemical properties to detect based on what is determined as the most accurate indicator for a particular surface 99/coating 98. Thus, the system 100, 100′ is able to be customized for each job in order to most effectively reduce the risk of surface damage.

FIG. 3 illustrates a flow chart of a method of removing a coating from a surface according to some embodiments. The controller 108 activates the laser source 102 and begins firing the laser light 97 at the low rate and/or intensity onto the target region of the surface at the step 302. Alternatively, the controller 108 is able to cause the laser source 102 to begin firing at the high rate and/or intensity as described in step 306 below. The detection element 106 detects if the coating 98 is currently separating from the target region of the surface 99, wherein the system 100, 100′ returns to step 302 (firing at the low rate/intensity) if removal is not detected and advances to step 306 if removal is detected at the step 304. In some embodiments, the detection element 106 detects the separation of the coating 98 from the target region by detecting one or more coating properties selected from the group consisting of the incandescence, acoustic signature, motion, fluorescence and chemical properties. In some embodiments, a signal 96 related to the one or more coating properties is transmitted by the routing element 104 to the detection element 106 such that the detection element 106 is able to detect if the coating 98 is separating from the target region. The controller 108 increases the rate and/or intensity at which the laser light 97 is directed onto the target region to a preselected high rate at the step 306. In some embodiments, the level of the preselected high rate is adjusted based on the one or more characteristics of the target region. In some embodiments, the one or more characteristics of the target region comprise a temperature of the target region. The detection element 106 detects if the coating 98 is currently separating from the target region of the surface 99, wherein the system 100, 100′ returns to step 306 (firing at the high rate/intensity) if removal is detected and advances to step 310 if removal is not detected at the step 308. The controller 108 determines if the detection element 106 has not detected the coating 98 separating from the target region for a predefined period, wherein if the period has not elapsed the system 100, 100′ returns to step 306 (firing at the high rate/intensity) and if the period has elapsed the system 100, 100′ returns to step 302 (firing at the low rate/intensity) at the step 310.

In some embodiments, the length of the period is adjusted automatically by the controller 108 or by a user based on one or more characteristics of the target region. In some embodiments, the level of the low rate is adjusted automatically by the controller 108 or by a user based on the one or more characteristics of the target region. In some embodiments, the high rate is equal to continuous projection of the laser light 97 onto the target region and the low rate is equal to none of the laser light 97 being projected onto the target region. In some embodiments, the high rate and the low rate are proportional to each other such that if one of the high or low rate is adjusted, the other rate is also adjusted in proportion. In some embodiments, one or more detection areas are defined and the rate at which the laser light 97 is directed onto the target region is decreased to the preselected low rate if the detection element 106 does not detect the coating 98 separating from the target region in one or more of the detection areas for the period. In some embodiments, the detection areas each comprise a portion of the target region. In some embodiments, the size of the detection areas are adjusted automatically by the system 100, 100′ or by a user based on the characteristics of the surface 99 and/or the coating 98. Accordingly, the coating removal system 100, 100′ is able to minimize the risk of damage to the surface 99 by dynamically detecting if the coating 98 is no longer being removed from the surface 99 such that the surface 99 is being directly subjected to damaging laser light 97.

Thus, it is clear that the coating removal system described herein has numerous advantages. Specifically, the coating removal system is able to efficiently remove coatings on a surface without damaging the surface by detecting when all the coating has been removed. Further, this damage prevention is able to effectively operate even if the distance and the angle from the laser optics to the substrate vary widely as is the case in many handheld laser de-coating systems on non-flat surfaces. Moreover, the damage prevention aspect is able to be dynamically adjusted based on the characteristics of the surface and/or the properties of the coating and its separation from the surface. As a result, the coating removal system is able to save energy and cost while still ensuring that no damage is caused to the surface by the system.

The present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention. Such reference herein to specific embodiments and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiment chosen for illustration without departing from the spirit and scope of the invention. 

What is claimed is:
 1. A laser-based coating removal apparatus to remove a coating from a surface, wherein the surface comprises the coating and a substrate, the laser-based coating apparatus comprising: a. a laser source to provide a laser light for removing the coating from a target region, wherein the laser source fires the laser light at a first rate to the target region and a second rate to the target region different from the first rate, wherein the first rate and the second rate are selected to remove the coating from the surface; b. a routing element coupled to the laser source and configured to direct the laser light onto the target region of the surface; c. a detection element that detects whether the coating has separated from the substrate in the target region of the surface by inputting a signal received from the surface in the target region, wherein the signal comprises data indicating one or more properties of the surface selected from a group consisting of incandescence, acoustic signature, motion and chemical properties; and d. a controller configured to adjust a current firing rate of the laser light based upon the signal received from the surface in the target region, and wherein the controller increases the current firing rate of the laser light from the first rate to the second rate at the target region when a current removal of the coating is detected at the target region, and wherein the target region is divided into a plurality of detection areas by the detection element and the current firing rate of the laser light is decreased to the first rate if the detection element fails to detect that the coating has separated from the substrate for a period of time and then the laser light is continuously fired as the firing rate is adjusted; wherein if the detection element detects that the coating has separated from the substrate in the target region for a period, the controller coupled to the detection element decreases an amount of energy per second directed onto the target region by the laser light from a non-zero preselected high value to a non-zero preselected low value; wherein the controller is able to adjust a length of the period based on the one or more properties of the surface in the target region.
 2. The apparatus of claim 1 wherein the routing element receives the signal from the surface and transmits the signal to the detection element such that the detection element is able to detect if the coating has separated from the substrate.
 3. The apparatus of claim 1 wherein an amount of energy per second directed onto the surface by the laser light is adjusted from a first non-zero amount to a second non-zero amount different than the first non-zero amount based on whether the detection element detects that the coating has separated from the substrate in the target region.
 4. The apparatus of claim 1 wherein the controller is able to adjust a quantity of the non-zero preselected low value based on the one or more properties of the surface in the target region.
 5. The apparatus of claim 4 wherein if the detection element detects the coating has not yet separated from the substrate in the target region for a duration while the amount of energy per second directed onto the target region by the laser light is equal to the non-zero preselected low value, the controller increases the amount of energy per second directed onto the target region by the laser light to the non-zero preselected high value.
 6. The apparatus of claim 5 wherein the controller is able to adjust a quantity of the non-zero preselected high value to a different quantity based on the one or more properties of the surface in the target region.
 7. The apparatus of claim 6 wherein the one or more properties of the surface consist of a temperature of the surface in the target region.
 8. The apparatus of claim 7 wherein the non-zero preselected high value is equal to a maximum amount of energy per second produced when the laser light has a maximum intensity and frequency and the non-zero preselected low value is equal to a minimum amount of energy per second produced when the laser light has a non-zero minimum intensity and frequency.
 9. The apparatus of claim 6 wherein the non-zero preselected high value and the non-zero preselected low value are proportional to each other such that if the non-zero preselected high value is adjusted, the non-zero preselected low value is adjusted in proportion to the non-zero preselected high value and if the non-zero preselected low value is adjusted, the non-zero preselected high value is adjusted in proportion to the non-zero preselected low value.
 10. A laser-based coating removal system comprising: a. a surface having a coating and a substrate; and b. a laser-based removal apparatus comprising: i. a laser source to provide a laser light for removing the coating from a target region, wherein the laser source fires the laser light at a first rate to the target region and a second rate to the target region different from the first rate, wherein the first rate and the second rate are selected to remove the coating from the surface; ii. a routing element coupled to the laser source and configured to direct the laser light onto the target region of the surface; iii. a detection element that detects whether the coating has separated from the substrate in the target region of the surface by inputting a signal received from the surface in the target region, wherein the target region is divided into a plurality of detection areas by the detection element and a firing rate of the laser light is decreased to a preselected low value if the detection element fails to detect that the coating has separated from the substrate for a period of time, and wherein the signal comprises data indicating one or more properties of the surface selected from a group consisting of incandescence, acoustic signature, motion and chemical properties; and iv. a controller configured to adjust the firing rate of the laser light based upon the signal received from the surface in the target region, and wherein the controller increases the firing rate of the laser light from the first rate to the second rate at the target region when a current removal of the coating is detected at the target region and then the laser light is continuously fired as the firing rate is adjusted; wherein if the detection element detects that the coating has separated from the substrate in the target region for a period, the controller coupled to the detection element decreases an amount of energy per second directed onto the target region by the laser light from a non-zero preselected high value to a non-zero preselected low value; wherein the controller is able to adjust a length of the period based on the one or more properties of the surface in the target region.
 11. The system of claim 10 wherein the routing element receives the signal from the surface and transmits the signal to the detection element such that the detection element is able to detect if the coating has separated from the substrate.
 12. The system of claim 10 wherein an amount of energy per second directed onto the surface by the laser light is adjusted from a first non-zero amount to a second non-zero amount different than the first non-zero amount based on whether the detection element detects that the coating has separated from the substrate in the target region.
 13. The apparatus of claim 10 wherein the controller is able to adjust a quantity of the non-zero preselected low value based on the one or more properties of the surface in the target region.
 14. The system of claim 13 wherein if the detection element detects the coating has not yet separated from the substrate in the target region for a duration while the amount of energy per second directed onto the target region by the laser light is equal to the non-zero preselected low value, the controller increases the amount of energy per second directed onto the target region by the laser light to the non-zero preselected high value.
 15. The system of claim 14 wherein the controller is able to adjust a quantity of the non-zero preselected high value to a different quantity based on the one or more properties of the surface in the target region.
 16. The system of claim 15 wherein the one or more properties of the surface consist of a temperature of the surface in the target region.
 17. The system of claim 16 wherein the non-zero preselected high value is equal to a maximum amount of energy per second produced when the laser light has a maximum intensity and frequency and the non-zero preselected low value is equal to a minimum amount of energy per second produced when the laser light has a non-zero minimum intensity and frequency.
 18. The system of claim 16 wherein the non-zero preselected high value and the non-zero preselected low value are proportional to each other such that if the non-zero preselected high value is adjusted, the non-zero preselected low value is adjusted in proportion to the non-zero preselected high value and if the non-zero preselected low value is adjusted, the non-zero preselected high value is adjusted in proportion to the non-zero preselected low value.
 19. A laser-based method of removing a coating from a surface, wherein the surface comprises the coating and a substrate, the method comprising: a. activating a laser source to provide a laser light for removing the coating from a target region, wherein the laser source fires the laser light at a first rate to the target region and a second rate to the target region different from the first rate, wherein the first rate and the second rate are selected to remove the coating from the surface; b. directing the laser light onto the target region of the surface with a routing element; c. detecting if the coating has separated from the substrate in the target region of the surface with a detection element by inputting a signal received from the surface in the target region, wherein the signal comprises data indicating one or more properties of the surface selected from a group consisting of incandescence, acoustic signature, motion and chemical properties; and d. adjusting a current firing rate of the laser light with a controller configured to adjust the current firing rate of the laser light based upon the signal received from the surface in the target region, and wherein the controller increases the current firing rate of the laser light from the first rate to the second rate at the target region when a current removal of the coating is detected at the target region, and wherein the target region is divided into a plurality of detection areas by the detection element and the current firing rate of the laser light is decreased to the first rate if the detection element fails to detect that the coating has separated from the substrate for a period of time and then the laser light is continuously fired as the firing rate is adjusted; wherein if the detection element detects that the coating has separated from the substrate in the target region for a period, the controller coupled to the detection element decreases an amount of energy per second directed onto the target region by the laser light from a non-zero preselected high value to a non-zero preselected low value; wherein the controller is able to adjust a length of the period based on the one or more properties of the surface in the target region.
 20. The method of claim 19 further comprising receiving a signal from the surface by the routing element and transmitting the signal with the routing element to the detection element such that the detection element is able to detect if the coating has separated from the substrate.
 21. The method of claim 19 further comprising adjusting an amount of energy per second directed onto the surface by the laser light from a first non-zero amount to a second non-zero amount different than the first non-zero amount based on whether the detection element detects that the coating has separated from the substrate in the target region.
 22. The method of claim 19 adjusting a quantity of the non-zero preselected low value based on the one or more properties of the surface in the target region.
 23. The method of claim 22 further comprising increasing the amount of energy per second directed onto the target region by the laser light to the non-zero preselected high value if the detection element detects the coating has not yet separated from the substrate in the target region for a duration while the amount of energy per second directed onto the target region by the laser light is equal to the non-zero preselected low value.
 24. The method of claim 23 further comprising adjusting a quantity of a preselected high value to a different quantity based on the one or more properties of the surface in the target region.
 25. The method of claim 24 wherein the one or more properties of the surface in the target region consist of a temperature of the surface in the target region.
 26. The method of claim 25 wherein the non-zero preselected high value is equal to a maximum amount of energy per second produced when the laser light has a maximum intensity and frequency and the non-zero preselected low value is equal to a minimum amount of energy per second produced when the laser light has a non-zero minimum intensity and frequency.
 27. The method of claim 25 wherein the non-zero preselected high value and the non-zero preselected low value are proportional to each other such that if the non-zero preselected high value is adjusted, the non-zero preselected low value is adjusted in proportion to the non-zero preselected high value and if the non-zero preselected low value is adjusted, the non-zero preselected high value is adjusted in proportion to the non-zero preselected low value.
 28. The method of claim 19 further comprising adjusting a size of the plurality of detection areas based on the one or more properties of the surface.
 29. A laser-based coating removal apparatus to remove a coating from a surface, wherein the surface comprises the coating and a substrate, the apparatus comprising: a. a laser source to provide a laser light for removing the coating from a target region, wherein the laser source fires the laser light at a first rate to the target region and a second rate to the target region different from the first rate, wherein the first rate and the second rate are selected to remove the coating from the surface; b. a routing element coupled to the laser source and configured to direct the laser light onto the target region of the surface; c. a detection element that detects whether the coating has separated from the substrate in the target region of the surface by inputting a signal received from the surface in the target region, wherein the signal comprises data indicating one or more properties of the surface selected from a group consisting of incandescence, acoustic signature, motion and chemical properties; and d. a controller configured to adjust a current firing rate of the laser light based upon the signal received from the surface in the target region, and, wherein the target region is divided into a plurality of detection areas by the detection element and the firing rate of the laser light is decreased to the first rate if the detection element fails to detect that the coating has separated from the substrate for a period of time and then the laser light is continuously fired as the firing rate is adjusted; wherein if the detection element detects that the coating has separated from the substrate in the target region for a period, the controller coupled to the detection element decreases an amount of energy per second directed onto the target region by the laser light from a non-zero preselected high value to a non-zero preselected low value; wherein the controller is able to adjust a length of the period based on the one or more properties of the surface in the target region. 